Follicle Stimulating Hormone
A pituitary hormone that stimulates sperm production in men and egg follicle development in women.
| Typical reference range (male) | 1.6–8 mIU/mL |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
FSH is released by the pituitary and acts on Sertoli cells in the testes to support sperm production and on ovarian follicles to promote their growth and estrogen production.
Why it matters
FSH helps evaluate fertility, ovarian reserve and menopause, and distinguishes primary from secondary hypogonadism. Persistently high FSH in women is a hallmark of menopause.
What a high result can mean
High FSH occurs with menopause or primary ovarian insufficiency, testicular failure (including after chemotherapy or with Klinefelter syndrome) and reduced ovarian reserve.
What a low result can mean
Low FSH occurs with pituitary or hypothalamic disorders, testosterone or anabolic steroid use, hormonal contraceptives, pregnancy, low body weight and high prolactin.
What affects the result
In women, a day 2-5 FSH is used for ovarian reserve; levels vary by cycle phase and are typically above ~25-30 after menopause. Biotin can interfere with some immunoassays.
Units and conversion
Usually reported in mIU/mL.
- From IU/L: multiply by 1 to get mIU/mL
- From mIU/L: multiply by 0.001 to get mIU/mL
Also called on lab reports
FSH, Follicle-Stimulating Hormone, Follicle Stimulating Hormone (FSH), FSH, Serum
Related tests: Sex Hormones
This page is educational and does not replace advice from a healthcare professional.